Effect of smoking on the serum levels of 25-hydroxyvitamin D depends on the assay employed. - Grimnes G; Almaas B; Eggen AE; Emaus N; Figenschau Y; Hopstock LA; Hutchinson MS; Methlie P; Mihailova A; Sneve M; Torjesen P; Wilsgaard T; et al. (European journal of endocrinology, 2010)